Apparatus supporting multi-radio coexistence

ABSTRACT

An apparatus supporting multi-radio coexistence is provided. The apparatus is configured to support coexistence between multiple transceiver circuits configured to communicate radio frequency (RF) signals in a shared RF medium. In examples discussed herein, one transceiver circuit asserts a medium access request via a standard-defined coexistence interface for communicating an RF signal in the shared RF medium. The transceiver circuit may be configured to assert or de-assert the medium access request in response to a variety of trigger events. Depending on whether the medium access request is granted, the transceiver circuit may start communicating the RF signal in the shared RF medium in different modes. As such, it may be possible to reduce medium access delay for the transceiver circuit requesting to access the shared RF medium, while protecting the transceiver circuit currently occupying the shared RF medium from undue interruption and interference.

FIELD OF THE DISCLOSURE

The technology of the disclosure relates generally to multi-radiocoexistence.

BACKGROUND

Wireless communication devices have become increasingly common incurrent society. The prevalence of these wireless communication devicesis driven in part by the many functions that are now enabled on suchdevices. Increased processing capabilities in such devices means thatwireless communication devices have evolved from being purecommunication tools into sophisticated multimedia centers that enableenhanced user experiences.

In this regard, a wireless communication device may employ a variety ofwireless communication technologies for enabling a variety of concurrentcommunication scenarios. For example, it may be necessary for thewireless communication device to support such wireless communicationtechnologies as wireless local area network (WLAN) based on theInstitute of Electrical and Electronics Engineers (IEEE) 802.11standard, low-rate wireless system (e.g., ZigBee) based on IEEE 802.15.4standard, and/or Bluetooth based on the Bluetooth Special Interest Group(SIG) specification.

Notably, the WLAN, the low-rate wireless system, and the Bluetoothtechnologies are configured to transmit and receive respective radiofrequency (RF) signals in the Industrial, Scientific, and Medical (ISM)band. As such, the WLAN, the low-rate wireless system, and the BluetoothRF signals can potentially interfere with each other when communicatedconcurrently. Given that a WLAN transmitter typically transmits the WLANRF signal, which also occupies a larger bandwidth of the ISM band, at amuch higher power than a low-rate wireless system transmitter does, alow-rate wireless system receiver may fall victim to the stronger WLANtransmission RF signal due to receiver blocking and/or saturation,particularly when the low-rate wireless system receiver is collocated inclose proximity (e.g., in a same form factor) to the WLAN transmitter.In this regard, it may be desired to protect the low-rate wirelesssystem receiver from being interfered by WLAN and/or Bluetoothtransmitters when the low-rate wireless system receiver is collocated inproximity to the WLAN/Bluetooth transmitters.

SUMMARY

Aspects disclosed in the detailed description include an apparatussupporting multi-radio coexistence. More specifically, the apparatus isconfigured to support coexistence between multiple transceiver circuitsconfigured to communicate radio frequency (RF) signals in a shared RFmedium, such as an Industrial, Scientific, and Medical (ISM) band. Inexamples discussed herein, one transceiver circuit asserts a mediumaccess request via a standard-defined coexistence interface forcommunicating (e.g., transmitting and/or receiving) an RF signal in theshared RF medium regardless of whether the shared RF medium is currentlyoccupied by another transceiver circuit. In a non-limiting example, thetransceiver circuit can be configured to assert or de-assert the mediumaccess request in response to a variety of trigger events. Depending onwhether the medium access request is granted, the transceiver circuitmay start communicating the RF signal in the shared RF medium indifferent modes. As such, it may be possible to reduce medium accessdelay for the transceiver circuit requesting to access the shared RFmedium, while protecting the transceiver circuit currently occupying theshared RF medium from undue interruption and interference.

In one aspect, a multi-radio apparatus is provided. The multi-radioapparatus includes a first transceiver circuit configured to communicatea first RF signal in a shared RF medium. The multi-radio apparatus alsoincludes a standard-defined coexistence interface coupled to the firsttransceiver circuit. The multi-radio apparatus also includes a secondtransceiver circuit coupled to the standard-defined coexistenceinterface. The second transceiver circuit is configured to assert amedium access request via the standard-defined coexistence interface forcommunicating a second RF signal in the shared RF medium in response toa first trigger event. The second transceiver circuit is also configuredto communicate the second RF signal in a first mode in response to amedium access grant for the medium access request being asserted via thestandard-defined coexistence interface. The second transceiver circuitis also configured to communicate the second RF signal in a second modein response to the medium access grant for the medium access request notbeing asserted. The second transceiver circuit is also configured tode-assert the medium access request in response to a second triggerevent.

In another aspect, a method for supporting coexistence between a firsttransceiver circuit configured to communicate a first RF signal and asecond transceiver circuit configured to communicate a second RF signalin a shared RF medium is provided. The method includes asserting amedium access request for communicating the second RF signal in theshared RF medium in response to a first trigger event. The method alsoincludes communicating the second RF signal in a first mode in responseto a medium access grant for the medium access request being asserted.The method also includes communicating the second RF signal in a secondmode in response to the medium access grant for the medium accessrequest not being asserted. The method also includes de-asserting themedium access request in response to a second trigger event.

Those skilled in the art will appreciate the scope of the disclosure andrealize additional aspects thereof after reading the following detaileddescription in association with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thisspecification illustrate several aspects of the disclosure and, togetherwith the description, serve to explain the principles of the disclosure.

FIG. 1A is a schematic diagram of an exemplary existing multi-radioapparatus in which a transmitting transceiver circuit can cause undueradio frequency (RF) interference to a receiving transceiver circuit dueto insufficient RF separation between the transmitting transceivercircuit and the receiving transceiver circuit;

FIG. 1B is a schematic diagram providing an exemplary illustration of astandard-defined coexistence interface for mitigating RF interferencecaused by the transmitting transceiver circuit to the receivingtransceiver circuit of FIG. 1A;

FIG. 2 is a schematic diagram of an exemplary multi-radio apparatusconfigured according to an embodiment of the present disclosure tosupport an enhanced multi-radio coexistence scheme between a firsttransceiver circuit and a second transceiver circuit based on astandard-defined coexistence interface;

FIG. 3 is a flowchart of an exemplary process that can be employed bythe second transceiver circuit of FIG. 2 to enable the enhancedcoexistence scheme in the multi-radio apparatus;

FIG. 4 is a time sequence diagram providing an exemplary time sequencefor acquiring a shared RF medium by the second transceiver circuit ofFIG. 2 to receive an RF signal;

FIG. 5 is a time sequence diagram providing an exemplary time sequencefor acquiring a shared RF medium by the second transceiver circuit ofFIG. 2 to transmit an RF signal; and

FIG. 6 is a time sequence diagram providing an exemplary time sequencefor acquiring a shared RF medium by the second transceiver circuit ofFIG. 2 to transmit and receive an RF signal.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the embodiments andillustrate the best mode of practicing the embodiments. Upon reading thefollowing description in light of the accompanying drawing figures,those skilled in the art will understand the concepts of the disclosureand will recognize applications of these concepts not particularlyaddressed herein. It should be understood that these concepts andapplications fall within the scope of the disclosure and theaccompanying claims.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element such as a layer, region, orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present.Likewise, it will be understood that when an element such as a layer,region, or substrate is referred to as being “over” or extending “over”another element, it can be directly over or extend directly over theother element or intervening elements may also be present. In contrast,when an element is referred to as being “directly over” or extending“directly over” another element, there are no intervening elementspresent. It will also be understood that when an element is referred toas being “connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” may be used herein to describe a relationshipof one element, layer, or region to another element, layer, or region asillustrated in the Figures. It will be understood that these terms andthose discussed above are intended to encompass different orientationsof the device in addition to the orientation depicted in the Figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including” when used herein specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

Aspects disclosed in the detailed description include an apparatussupporting multi-radio coexistence. More specifically, the apparatus isconfigured to support coexistence between multiple transceiver circuitsconfigured to communicate radio frequency (RF) signals in a shared RFmedium, such as an Industrial, Scientific, and Medical (ISM) band. Inexamples discussed herein, one transceiver circuit asserts a mediumaccess request via a standard-defined coexistence interface forcommunicating (e.g., transmitting and/or receiving) an RF signal in theshared RF medium regardless of whether the shared RF medium is currentlyoccupied by another transceiver circuit. In a non-limiting example, thetransceiver circuit can be configured to assert or de-assert the mediumaccess request in response to a variety of trigger events. Depending onwhether the medium access request is granted, the transceiver circuitmay start communicating the RF signal in the shared RF medium indifferent modes. As such, it may be possible to reduce medium accessdelay for the transceiver circuit requesting to access the shared RFmedium, while protecting the transceiver circuit currently occupying theshared RF medium from undue interruption and interference to helpimprove link quality.

Before discussing the apparatus of the present disclosure, a briefoverview of a standard-defined coexistence interface between a pair ofcollocated transceiver circuits is first provided with reference toFIGS. 1A and 1B. The discussion of specific exemplary aspects of theapparatus supporting multi-radio coexistence according to the presentdisclosure starts below with reference to FIG. 2.

FIG. 1A is a schematic diagram of an exemplary existing multi-radioapparatus 10 in which a transmitting transceiver circuit 12 can causeundue RF interference to a receiving transceiver circuit 14 due toinsufficient RF separation between the transmitting transceiver circuit12 and the receiving transceiver circuit 14. The transmittingtransceiver circuit 12 may be a wireless local area network (WLAN)transceiver circuit configured to transmit a WLAN RF signal 16 to a WLANreceiver 18 in accordance with medium access control (MAC) layer andphysical (PHY) layer specifications as defined by the Institute ofElectrical and Electronics Engineers (IEEE) 802.11 standard. Thetransmitting transceiver circuit 12 may also be a Bluetooth (BT)transceiver circuit configured to transmit a BT RF signal 20 to a BTreceiver 22 in accordance to MAC layer and PHY layer specifications asdefined by the Bluetooth Special Interest Group (SIG) standard. Thereceiving transceiver circuit 14 may be a low-rate wireless system(e.g., ZigBee) transceiver circuit configured to receive a low-rate RFsignal 24 from a low-rate wireless system transmitter 26 in accordanceto MAC layer and PHY layer specifications as defined by the IEEE802.15.4 standard.

The transmitting transceiver circuit 12 is configured to transmit theWLAN RF signal 16 and/or the BT RF signal 20, and the receivingtransceiver circuit 14 is configured to receive the low-rate RF signal24 in a shared RF medium 28. The shared RF medium 28 may correspond tothe Industrial, Scientific, and Medical (ISM) band occupying a 2.4-2.5GHz RF spectrum.

The transmitting transceiver circuit 12 and the receiving transceivercircuit 14 are collocated in the existing multi-radio apparatus 10.Hereinafter, a pair of transceiver circuits is referred to as beingcollocated when the transceiver circuits are provided in a same formfactor and/or separated by 10-40 dB of RF separation. Notably, thetransmitting transceiver circuit 12 may transmit at a significantlyhigher power than the low-rate wireless system transmitter 26 does. As aresult, the WLAN RF signal 16 and/or the BT RF signal 20 may block andsaturate the receiving transceiver circuit 14. Consequently, thereceiving transceiver circuit 14 may be impaired to receive the low-rateRF signal 24.

To help mitigate RF interference between the transmitting transceivercircuit 12 and the receiving transceiver circuit 14 collocated in theexisting multi-radio apparatus 10, the IEEE 802.15.2 standard hasdefined a standard-defined coexistence interface 30, which is also knownas a two-wire coexistence interface. Hereinafter, the standard-definedcoexistence interface 30 as defined by the IEEE 802.15.2 is referred toas a standard-defined coexistence interface.

FIG. 1B is a schematic diagram providing an exemplary illustration ofthe standard-defined coexistence interface 30 for mitigating RFinterference caused by the transmitting transceiver circuit 12 to thereceiving transceiver circuit 14 of FIG. 1A. In a non-limiting example,the transmitting transceiver circuit 12 is currently transmitting theWLAN RF signal 16 (not shown) and/or the BT RF signal 20 (not shown) inthe shared RF medium 28 (not shown), while the receiving transceivercircuit 14 is prepared to receive the low-rate RF signal 24 (not shown)via the shared RF medium 28. In this regard, the receiving transceivercircuit 14 provides a medium access request 32 to the transmittingtransceiver circuit 12 via a first wire 34 of the standard-definedcoexistence interface 30. In a non-limiting example, the receivingtransceiver circuit 14 may initiate the medium access request 32 byasserting the first wire 34 to a logical HIGH. Upon receiving the mediumaccess request 32, the transmitting transceiver circuit 12 may respondin a number of ways.

In one embodiment, the transmitting transceiver circuit 12 can suspendtransmission of the WLAN RF signal 16 and/or the BT RF signal 20immediately. Subsequently, the transmitting transceiver circuit 12provides a medium access grant 36 to the receiving transceiver circuit14 via a second wire 38 in the standard-defined coexistence interface30. In a non-limiting example, the transmitting transceiver circuit 12may initiate the medium access grant 36 by asserting the second wire 38to a logical HIGH. Accordingly, the receiving transceiver circuit 14 canstart receiving the low-rate RF signal 24 without interference from theWLAN RF signal 16 and/or the BT RF signal 20. Upon successful completionof receiving the low-rate RF signal 24, the receiving transceivercircuit 14 may cancel the medium access request 32 by de-asserting thefirst wire 34 to a logical LOW. In response, the transmittingtransceiver circuit 12 cancels the medium access grant 36 byde-asserting the second wire 38 to a logical LOW and resumestransmission of the WLAN RF signal 16 and/or the BT RF signal 20. Byimmediately suspending transmission of the transmitting transceivercircuit 12, it may be possible to reduce medium access delay of thereceiving transceiver circuit 14. However, the reduction in mediumaccess delay may come at an expense of potential disruption to the WLANRF signal 16 and/or the BT RF signal 20.

In another embodiment, the transmitting transceiver circuit 12 cansuspend transmission of the WLAN RF signal 16 and/or the BT RF signal 20after completing current transmission. Subsequently, the transmittingtransceiver circuit 12 provides the medium access grant 36 to thereceiving transceiver circuit 14 via the second wire 38 in thestandard-defined coexistence interface 30. In a non-limiting example,the transmitting transceiver circuit 12 may initiate the medium accessgrant 36 by asserting the second wire 38 to a logical HIGH. Accordingly,the receiving transceiver circuit 14 can start receiving the low-rate RFsignal 24 without interference from the WLAN RF signal 16 and/or the BTRF signal 20. Upon successful completion of receiving the low-rate RFsignal 24, the receiving transceiver circuit 14 may cancel the mediumaccess request 32 by de-asserting the first wire 34 to a logical LOW. Inresponse, the transmitting transceiver circuit 12 cancels the mediumaccess grant 36 by de-asserting the second wire 38 to a logical LOW andresumes transmission of the WLAN RF signal 16 and/or the BT RF signal20. In this case, the receiving transceiver circuit 14 may suffer anincreased medium access delay, thus causing a potential disruption tothe low-rate RF signal 24.

In another embodiment, the transmitting transceiver circuit 12 may choseto ignore the medium access request 32. Accordingly, the transmittingtransceiver circuit 12 maintains the second wire 38 as the logical LOW.In this regard, the receiving transceiver circuit 14 may be denied achance to receive the low-rate RF signal 24 in an interference-protectedmanner.

As discussed above, the standard-defined coexistence interface 30 mayhelp mitigate RF interference caused by the transmitting transceivercircuit 12 to the receiving transceiver circuit 14 in the existingmulti-radio apparatus 10. However, depending on different ways ofhandling the medium access request 32, the transmitting transceivercircuit 12 and/or the receiving transceiver circuit 14 may be subject toundue interruption in transmitting/receiving respective RF signals.Hence, it may be desired to enhance the existing multi-radio apparatus10 to reduce medium access delay of the receiving transceiver circuit14, while protecting the transmitting transceiver circuit 12 from undueinterruption and interference.

In this regard, FIG. 2 is a schematic diagram of an exemplarymulti-radio apparatus 40 configured according to an embodiment of thepresent disclosure to support an enhanced multi-radio coexistence schemebetween a first transceiver circuit 42 and a second transceiver circuit44 based on a standard-defined coexistence interface 46. In examplesdiscussed herein, the first transceiver circuit 42 can be a WLAN/BTtransceiver circuit configured to communicate a WLAN/BT RF signal 48(also referred to as “first RF signal”) in a shared RF medium 50. Thesecond transceiver circuit 44 may be a low-rate wireless system (e.g.,ZigBee) transceiver circuit configured to communicate a low-rate RFsignal 52 (also referred to as “second RF signal”) in the shared RFmedium 50. The shared RF medium 50 may be an ISM band located in the2.4-2.5 GHz RF spectrum.

The first transceiver circuit 42 may be coupled to a first antenna(s) 54via a first front-end circuit 56, which may include a power amplifier(PA) (not shown) for amplifying the first RF signal 48 prior to beingradiated by the first antenna(s) 54 and a low-noise amplifier (LNA) (notshown) for amplifying the first RF signal 48 after being absorbed by thefirst antenna(s) 54. The second transceiver circuit 44 may be coupled toa second antenna(s) 58 via a second front-end circuit 60, which mayinclude a PA (not shown) for amplifying the second RF signal 52 prior tobeing radiated by the second antenna(s) 58 and an LNA (not shown) foramplifying the second RF signal 52 after being absorbed by the secondantenna(s) 58.

The standard-defined coexistence interface 46 is identical to thestandard-defined coexistence interface 30 in FIGS. 1A and 1B.Accordingly, the standard-defined coexistence interface 46 includes afirst wire 62 and a second wire 64 that are identical to the first wire34 and the second wire 38 in the standard-defined coexistence interface30, respectively. In this regard, the multi-radio apparatus 40 isconfigured to support the enhanced coexistence scheme between the firsttransceiver circuit 42 and the second transceiver circuit 44 withoutrequiring any change to the standard-defined coexistence interface 46.

The first transceiver circuit 42 is identical to the transmittingtransceiver circuit 12 in FIG. 1A. In this regard, the multi-radioapparatus 40 is able to support the enhanced coexistence scheme withoutrequiring intrusive change in the first transceiver circuit 42. As such,it may be possible to employ any standard-compliant WLAN/BT transceivercircuit in a plug-and-play manner, thus helping to reduce complexity andcosts associated with implementation of the enhanced coexistence scheme.

The second transceiver circuit 44 is functionally equivalent to thereceiving transceiver circuit 14 in FIG. 1A. However, the secondtransceiver circuit 44 is modified from the receiving transceivercircuit 14 to incorporate additional functionalities for enabling theenhanced coexistence scheme of the present disclosure. Morespecifically, the second transceiver circuit 44 may be configured toenable the enhanced coexistence scheme based on a process, as discussednext in FIG. 3.

FIG. 3 is a flowchart of an exemplary process 100 that can be employedby the second transceiver circuit 44 of FIG. 2 to enable the enhancedcoexistence scheme in the multi-radio apparatus 40. The process 100includes the additional functionalities being incorporated into thesecond transceiver circuit 44 of FIG. 2 for enabling the enhancedcoexistence scheme.

According to the process 100, the second transceiver circuit 44 assertsa medium access request 66 via the standard-defined coexistenceinterface 46 for communicating (transmitting or receiving) the second RFsignal 52 in the shared RF medium 50 in response to a first triggerevent (block 102). In a non-limiting example, the second transceivercircuit 44 can assert the medium access request 66 by toggling the firstwire 62 in the standard-defined coexistence interface 46 from a logicalLOW to a logical HIGH.

The first transceiver circuit 42, which may be currently occupying theshared RF medium 50, may become aware of the medium access request 66 bydetecting the first wire 62 being togged to the logical HIGH. Inresponse, the first transceiver circuit 42 may grant the medium accessrequest 66, either immediately or after a short delay. In a non-limitingexample, the short delay can be caused by hardware implementation and/orsoftware function calls. In addition, the short delay may also be causedas a result of the first transceiver circuit 42 attempting to completean ongoing transmission/reception prior to yielding the shared RF medium50 to the second transceiver circuit 44. Accordingly, the firsttransceiver circuit 42 may assert a medium access grant 68, for example,by toggling the second wire 64 in the standard-defined coexistenceinterface 46 from a logical LOW to a logical HIGH. The secondtransceiver circuit 44 may determine that the medium access request 66is granted when the second wire 64 is toggled to the logical HIGH.

In this regard, the second transceiver circuit 44 is configured tocommunicate the second RF signal 52 in a first mode in response to themedium access grant 68 for the medium access request 66 being assertedvia the standard-defined coexistence interface 46 (block 104). Incontrast, the second transceiver circuit 44 is configured to communicatethe second RF signal 52 in a second mode in response to the mediumaccess grant 68 for the medium access request 66 not being asserted viathe standard-defined coexistence interface 46 (block 106).

The second transceiver circuit 44 is further configured to de-assert themedium access request 66 in response to a second trigger event (block108). The second transceiver circuit 44 may de-assert the medium accessrequest 66 by toggling the first wire 62 in the standard-definedcoexistence interface 46 from the logical HIGH to the logical LOW.Accordingly, the first transceiver circuit 42 may then toggle the secondwire 64 from the logical HIGH to the logical LOW.

With reference back to FIG. 2, the first trigger event that causes thesecond transceiver circuit 44 to assert the medium access request 66 caninclude a variety of predefined events. In one example, the secondtransceiver circuit 44 is preparing to receive the second RF signal 52via the shared RF medium 50. In this regard, the first trigger event cancorrespond to a successful reception of a preamble/start-frame delimiter(SFD) of an incoming packet(s) 70 in the second RF signal 52. In anotherexample, the second transceiver circuit 44 is preparing to transmit thesecond RF signal 52 via the shared RF medium 50. In this regard, thefirst trigger event can correspond to a successful detection of astandardized trigger event, such as an IEEE 802.15.4 MAC layer command.

If the first transceiver circuit 42 asserts the medium access grant 68immediately upon detecting the medium access request 66, the secondtransceiver circuit 44 is configured to communicate (transmit orreceive) the second RF signal 52 in the first mode. In the first mode,the second transceiver circuit 44 may activate the PA in the secondfront-end circuit 60 to amplify the second RF signal 52 prior to beingradiated by the second antenna(s) 58. In this regard, the first mode maybe seen as a “full-power” mode.

In contrast, if the first transceiver circuit 42 does not assert themedium access grant 68 immediately or within a defined delay (e.g., 200μs) upon detecting the medium access request 66, the second transceivercircuit 44 is configured to communicate (transmit or receive) the secondRF signal 52 in the second mode. In the second mode, the secondtransceiver circuit 44 may deactivate the PA in the second front-endcircuit 60 such that the second RF signal 52 is not amplified prior tobeing radiated by the second antenna(s) 58. In this regard, the secondmode may be seen as a “reduced-power” mode. Moreover, the secondtransceiver circuit 44 may cause the second RF signal 52 to beattenuated prior to being radiated by the second antenna(s) 58. In anon-limiting example, the second RF signal 52 can be attenuated to adefined power level that is below a receiver saturation threshold of thefirst transceiver circuit 42 such that the second RF signal 52 does notinterfere with the first transceiver circuit 42 when the second RFsignal 52 is transmitted in a different channel from the firsttransceiver circuit 42.

Despite being transmitted at a reduced power level, an outgoingpacket(s) 72 in the second RF signal 52 may still be received by anearby low-rate wireless system receiver (not shown). Thus, bytransmitting the second RF signal 52 in the second mode, it may bepossible to reduce a medium access delay for the second transceivercircuit 44 even when the first transceiver circuit 42 does not yield theshared RF medium 50 in a timely fashion. Notably, the second transceivercircuit 44 may not know whether the outgoing packet(s) 72 has beenreceived correctly in absence of an acknowledgement (ACK) from thelow-rate wireless system receiver. In this regard, the secondtransceiver circuit 44 may be configured to retransmit the outgoingpacket(s) 72 when the first transceiver circuit 42 asserts the mediumaccess grant 68.

In the unlikely event that the first transceiver circuit 42 denies themedium access request 66, the second transceiver circuit 44 may beconfigured to cause the first transceiver circuit 42 to be decoupledfrom the first front-end circuit 56 and the first antenna(s) 54. Thesecond transceiver circuit 44 may set a delay time-out timer immediatelyupon asserting the medium access request 66. Accordingly, the secondtransceiver circuit 44 may cause the first transceiver circuit 42 to bedecoupled from the first front-end circuit 56 and the first antenna(s)54 upon expiration of the delay time-out timer. In this regard, thesecond transceiver circuit 44 can forcefully take over the shared RFmedium at an expense of the first transceiver circuit 42. Notably, thisscenario should not happen if the first transceiver circuit 42 isconfigured to operate in compliance with the standard-definedcoexistence interface 46. The second transceiver circuit 44 may resetthe delay time-out timer in response to the second wire 64 beingasserted to the logical HIGH or upon successful reception of an ACK.

Given that the second RF signal 52 is often communicated with arelatively longer duty-cycle, the second transceiver circuit 44 isconfigured to occupy the shared RF medium 50 longer than needed. In thisregard, the second transceiver circuit 44 is configured to de-assert themedium access request 66 in response to the second trigger event.

In one non-limiting example, the second transceiver circuit 44 caninitiate a predefined time-out timer immediately when the medium accessgrant 68 is asserted. The predefined time-out timer may be longer than atemporal duration for transmitting/receiving an 802.15.4 packet and/orthe duration for completing an MAC layer retransmission(s). In thisregard, the second trigger event can correspond to an expiration of thepredefined time-out timer. By de-asserting the medium access request 66based on the predefined time-out timer, it may be possible to preventthe second transceiver circuit 44 from holding the shared RF medium 50for an excessive length of time, thus helping data throughput on theshared RF medium 50.

In another non-limiting example, the second transceiver circuit 44acquires the shared RF medium 50 for receiving the incoming packet(s) 70in the second RF signal 52. In this regard, the second trigger event maycorrespond to a successful transmission of an ACK by the secondtransceiver circuit 44 in response to successful reception of theincoming packet(s) 70.

In another non-limiting example, the second transceiver circuit 44acquires the shared RF medium 50 for transmitting the outgoing packet(s)72 in the second RF signal 52. In this regard, the second trigger eventmay correspond to a successful reception of an ACK by the secondtransceiver circuit 44 in response to the transmission of the outgoingpacket(s) 72.

As discussed earlier, the second transceiver circuit 44 may assert themedium access request 66 in response to detection of the preamble of theincoming packet(s) 70. In this regard, the second transceiver circuit 44may be further configured to examine the destination address of theincoming packet(s) 70 to help determine whether the incoming packet(s)70 is destined to the second transceiver circuit 44. In case theincoming packet(s) 70 is not destined to the second transceiver circuit44, the incoming packet(s) 70 may be treated as an invalid incomingpacket(s). Accordingly, the second trigger event can correspond todetection of the invalid incoming packet(s).

Some specific non-limiting examples of the enhanced coexistence schemeare now discussed in reference to FIGS. 4-6 below. Common elementsbetween FIGS. 2 and 4-6 are shown therein with common element numbersand will not be re-described herein.

FIG. 4 is a time sequence diagram providing an exemplary time sequence74 for acquiring the shared RF medium 50 by the second transceivercircuit 44 of FIG. 2 to receive the second RF signal 52. At time T1, thesecond transceiver circuit 44 detects a preamble/SFD 76 of the incomingpacket(s) 70 (first trigger event) and asserts the medium access request66 on the first wire 62. In the meantime, the first transceiver circuit42 is communicating the first RF signal 48 on the shared RF medium 50(not shown). At time T2, the first transceiver circuit 42 asserts themedium access grant 68 on the second wire 64 and suspends communicationof the first RF signal 48. The second transceiver circuit 44, one theother hand, may have missed at least part of the incoming packet(s) 70and does not acknowledge reception of the incoming packet(s) 70. As aresult, a retransmitted incoming packet(s) 70(1) may be sent andsubsequently received by the second transceiver circuit 44. In response,the second transceiver circuit 44 transmits an ACK 78 (second triggerevent) at time T3 and de-asserts the medium access request 66 at timeT4. In response, at time T5, the first transceiver circuit 42 de-assertsthe medium access grant 68 and resumes communication of the first RFsignal 48 thereafter.

FIG. 5 is a time sequence diagram providing an exemplary time sequence80 for acquiring the shared RF medium 50 by the second transceivercircuit 44 of FIG. 2 to transmit the second RF signal 52. At time T1,the second transceiver circuit 44 asserts the medium access request 66on the first wire 62 and starts transmitting the outgoing packet(s) 72in the second mode. In this regard, the outgoing packet(s) 72 istransmitted at a reduced power level and may not be correctly receivedby an intended receiver. As a result, the second transceiver circuit 44may not receive an ACK 82 as expected. At time T2, the first transceivercircuit 42 asserts the medium access grant 68 on the second wire 64. Incase the second transceiver circuit 44 did not receive the ACK 82 asexpected, the second transceiver circuit 44 retransmits the outgoingpacket(s) 72(1) in the first mode. At time T3, the second transceivercircuit 44 receives the ACK 82 (second trigger event) for theretransmitted outgoing packet(s) 72(1). Accordingly, the secondtransceiver circuit 44 de-asserts the medium access request 66. Inresponse, at time T4, the first transceiver circuit 42 de-asserts themedium access grant 68 and resumes communication of the first RF signal48 thereafter.

FIG. 6 is a time sequence diagram providing an exemplary time sequence84 for acquiring the shared RF medium 50 by the second transceivercircuit 44 of FIG. 2 to transmit and receive the second RF signal 52. Attime T1, the second transceiver circuit 44 receives a preamble/SFD 76 ofan IEEE 802.15.4 ZigBee cluster library (ZCL) request command (firsttrigger event) in the incoming packet(s) 70. Accordingly, the secondtransceiver circuit 44 asserts the medium access request 66 on the firstwire 62. In the meantime, the first transceiver circuit 42 is stillcommunicating with the first RF signal 48 on the shared RF medium 50(not shown). As a result, the second transceiver circuit 44 may notreceive the incoming packet(s) 70 correctly and thus may not be able toacknowledge the incoming packet(s) 70. At time T2, the first transceivercircuit 42 asserts the medium access grant 68 on the second wire 64.Accordingly, the second transceiver circuit 44 may receive theretransmitted incoming packet(s) 70(1) and transmit the ACK 78.Subsequently, the second transceiver circuit 44 may transmit a number ofoutgoing packets 72 and receive a number of corresponding ACKs 82. Thesecond transceiver circuit 44 may conclude a packet exchange bytransmitting an IEEE 802.15.4 ZCL response packet as the final outgoingpacket(s) 72 (second trigger event) and subsequently de-assert themedium access request 66 at time T3. In response, at time T4, the firsttransceiver circuit 42 de-asserts the medium access grant 68 and resumescommunication of the first RF signal 48 thereafter.

Those skilled in the art will recognize improvements and modificationsto the embodiments of the present disclosure. All such improvements andmodifications are considered within the scope of the concepts disclosedherein and the claims that follow.

1. A multi-radio apparatus comprising: a first transceiver circuitconfigured to communicate a first radio frequency (RF) signal in ashared RF medium; a standard-defined coexistence interface coupled tothe first transceiver circuit; and a second transceiver circuit coupledto the standard-defined coexistence interface and configured to: asserta medium access request via the standard-defined coexistence interfacefor communicating a second RF signal in the shared RF medium in responseto a first trigger event; transmit the second RF signal in a first modein response to a medium access grant for the medium access request beingasserted via the standard-defined coexistence interface; transmit thesecond RF signal in a second mode in response to the medium access grantfor the medium access request not being asserted; and de-assert themedium access request in response to a second trigger event.
 2. Themulti-radio apparatus of claim 1 wherein the first trigger eventcorresponds to reception of a preamble/start-frame delimiter (SFD) of anincoming packet in the second RF signal.
 3. The multi-radio apparatus ofclaim 1 wherein the first trigger event corresponds to reception of aZigBee cluster library (ZCL) request.
 4. The multi-radio apparatus ofclaim 1 wherein, in the first mode, the second transceiver circuit isfurther configured to cause the second RF signal to be amplified priorto transmission in the shared RF medium in the first mode.
 5. Themulti-radio apparatus of claim 1 wherein the second transceiver circuitis further configured to cause the second RF signal to not be amplifiedprior to transmission in the shared RF medium in the second mode.
 6. Themulti-radio apparatus of claim 1 wherein the second transceiver circuitis further configured to cause the second RF signal to be attenuatedprior to transmission in the shared RF medium in the second mode.
 7. Themulti-radio apparatus of claim 1 wherein the second transceiver circuitis further configured to: de-assert the medium access request inresponse to the second trigger event indicative of transmitting anacknowledge (ACK) packet in the shared RF medium after receiving anincoming packet in the second RF signal; de-assert the medium accessrequest in response to the second trigger event indicative of receivingthe ACK packet in the shared RF medium after transmitting an outgoingpacket in the second RF signal; de-assert the medium access request inresponse to the second trigger event indicative of an expiration of apredefined time-out timer; de-assert the medium access request inresponse to the second trigger event indicative of a detection of aninvalid incoming packet received in the second RF signal; and de-assertthe medium access request in response to receiving a ZigBee clusterlibrary (ZCL) response.
 8. The multi-radio apparatus of claim 1 whereinthe second transceiver circuit is further configured to de-assert themedium access request in response to the second trigger event indicativeof transmitting an acknowledge (ACK) packet in the shared RF mediumafter receiving an incoming packet in the second RF signal.
 9. Themulti-radio apparatus of claim 1 wherein the second transceiver circuitis further configured to de-assert the medium access request in responseto the second trigger event indicative of receiving an acknowledge (ACK)packet in the shared RF medium after transmitting an outgoing packet inthe second RF signal.
 10. The multi-radio apparatus of claim 1 whereinthe second transceiver circuit is further configured to de-assert themedium access request in response to the second trigger event indicativeof an expiration of a predefined time-out timer.
 11. The multi-radioapparatus of claim 1 wherein the second transceiver circuit is furtherconfigured to de-assert the medium access request in response to thesecond trigger event indicative of detection of an invalid incomingpacket received in the second RF signal.
 12. A method for supportingcoexistence between a first transceiver circuit configured tocommunicate a first radio frequency (RF) signal and a second transceivercircuit configured to communicate a second RF signal in a shared RFmedium comprising: asserting a medium access request for communicatingthe second RF signal in the shared RF medium in response to a firsttrigger event; transmitting the second RF signal in a first mode inresponse to a medium access grant for the medium access request beingasserted; transmitting the second RF signal in a second mode in responseto the medium access grant for the medium access request not beingasserted; and de-asserting the medium access request in response to asecond trigger event.
 13. The method of claim 12 further comprisingasserting the medium access request in response to detecting apreamble/start-frame delimiter (SFD) of an incoming packet in the secondRF signal.
 14. The method of claim 12 further comprising asserting themedium access request in response to receiving a ZigBee cluster library(ZCL) request.
 15. The method of claim 12 further comprising causing thesecond RF signal to be amplified prior to transmission in the shared RFmedium in the first mode.
 16. The method of claim 12 further comprisingcausing the second RF signal to not be amplified prior to transmissionin the shared RF medium in the second mode.
 17. The method of claim 12further comprising causing the second RF signal to be attenuated priorto transmission in the shared RF medium in the second mode.
 18. Themethod of claim 12 further comprising: de-asserting the medium accessrequest in response to the second trigger event indicative oftransmitting an acknowledge (ACK) packet in the shared RF medium afterreceiving an incoming packet in the second RF signal; de-asserting themedium access request in response to the second trigger event indicativeof receiving the ACK packet in the shared RF medium after transmittingan outgoing packet in the second RF signal; de-asserting the mediumaccess request in response to the second trigger event indicative of anexpiration of a predefined time-out timer; de-asserting the mediumaccess request in response to the second trigger event indicative of adetection of an invalid incoming packet received in the second RFsignal; and de-asserting the medium access request in response toreceiving a ZigBee cluster library (ZCL) response.
 19. The method ofclaim 12 further comprising de-asserting the medium access request inresponse to the second trigger event indicative of transmitting anacknowledge (ACK) packet in the shared RF medium after receiving anincoming packet in the second RF signal.
 20. The method of claim 12further comprising de-asserting the medium access request in response tothe second trigger event indicative of receiving an acknowledge (ACK)packet in the shared RF medium after transmitting an outgoing packet inthe second RF signal.
 21. The method of claim 12 further comprisingde-asserting the medium access request in response to the second triggerevent indicative of an expiration of a predefined time-out timer. 22.The method of claim 12 further comprising de-asserting the medium accessrequest in response to the second trigger event indicative of adetection of an invalid incoming packet received in the second RFsignal.